1. Field of the Invention
The present invention relates to a microorganism belonging to the genus Escherichia sp. having a sucrose assimilability and an L-amino acid producing ability, which is obtained by introducing a gene encoding a sucrose assimilative microorganism-derived sucrose metabolic enzyme to a sucrose non-assimilative microorganism belonging to the genus Escherichia sp. having an L-amino acid producing ability and a sucrose PTS (phosphoenolpyruvate dependent sucrose phosphotransferase system) activity, and a method for producing an L-amino acid using the same.
2. Description of the Related Art
Due to the growing demand for bio-fuel production and crop failures caused by unusual climate, the price of starch sugar mainly used in industrial fermentation has rapidly increased. Alternatively, the use of sucrose or molasses containing a high concentration of sucrose, cheaper than starch sugar, as a carbon source in industrial fermentation, is advantageous to ensure the cost competitiveness.
Approximately 50% of wild-type naturally occurring E. coli is able to metabolize sucrose, but E. coli K12 strain, B strain, C strain or the like usually used in industrial fermentation, have no ability to assimilate sucrose (Mol. Microbiol, (1998) 2:1-8, Can. J. Microbiol. (1999) 45:418-422). Therefore, one of the most important challenges in the fermentation industry is the identification of genes involved in sucrose assimilation, the establishment of enhanced sucrose assimilation-related genes by improvement, and the application of the genes to the sucrose non-assimilative, industrial E. coli strains for the production of desired metabolites.
To impart a sucrose-assimilability to industrial E. coli strains, methods of introducing genes or gene cluster involved in sucrose assimilation, derived from a microorganism having a sucrose-assimilability have been generally used. For example, a method of imparting sucrose-assimilability to E. coli K12 by transformation with the scr regulon that is present in the species Salmonella belonging to the family Enterobacteriaceae (J. Bacteriol. (1982) 151:68-76, Mol. Microbiol. (1998) 2:1-8, J. Bacteriol, (1991) 173:7464-7470, U.S. Pat. No. 7,179,623), Klebsiella pneumoniae (J. Gen. Microbiol. (1988) 134:1635-1644), and Erwinia amylovora (J. Bacteriol. (2000) 182:5351-5358) has been well known in the art. Introduction of the csc regulon derived from non-K12 E. coli or pathogenic E. coli having the sucrose-assimilability (Appl. Environ. Microbiol. (1992) 58:2081-2088, U.S. Pat. No. 6,960,455), introduction of gene cluster involved in sucrose assimilation that is present in conjugative plasmid scr53 isolated from E. coli AB1281 (U.S. Pat. No. 4,806,480), and introduction of scr regulon and sac operon derived from Gram-positive microorganism, Streptococcus mutans (J. Bacterial, (1989) 171:263-271) and Bacillus subtilis (J. Bacteriol, (1989) 171:1519-1523) are also known. U.S. Pat. No. 7,179,623 discloses a method of producing lysine, isoleucine and valine using E. coli K12 that is prepared by introducing an E. coli VKPM B-7915-derived scr regulon thereto.
However, there is still a need of an industrial microorganism having an efficient sucrose utilization system and a fermentation method using the same. Therefore, the present inventors found that an L-amino acid can be produced from sucrose at a high yield using an L-amino acid-producing microorganism belonging to the genus Escherichia sp., which is prepared by introducing a gene cluster involved in sucrose assimilation, derived from a sucrose assimilative Klebsiella pneumoniae, thereby completing the present invention.